The present invention relates to a method and an apparatus for driving a motor for use for example in an air conditioner and, more particularly, to generation of switching signals for driving a motor on the basis of a PWM (pulse width modulation) system.
As one of the conventional systems of the described type, there is a system disclosed in the U.S. Pat. No. 4,698,744. The system disclosed in the USP is such that is adapted, in controlling operation (number of revolutions) of a single motor by means of a single microprocessor, to generate six switching signals in the microprocessor and control the operation of the motor with these switching signals.
Since, in the conventional driving method, six switching signals are output from the microprocessor, the microprocessor has to have at least six output ports (terminals) therefor. Hence, when this microprocessor is used also for controlling other electric apparatuses, there arises a problem that the ports become insufficient in number for controlling such other apparatuses.
The present invention was made for solving the above mentioned problem. Accordingly, an object of the present invention is to provide a method and an apparatus for driving a motor in which the difficulty of insufficiency of ports in number is solved.
Another object of the present invention is to drive a plurality of motors and other electric apparatuses with plural sets of outputs based on a PWM system provided by the use of a single microprocessor.